The present invention relates to high velocity fin stabilized armor piercing projectiles and more particularly relates to projectiles of such type which are self-destructing.
Armor piercing projectiles can be generally divided into two main classes: armor piercing projectiles characterized by a relatively low length-to-diameter (L/D) ratio such as 3-5 which are fired by a gun or cannon with a rifled bore which provides gyroscopic stability during the trajectory; and armor piercing projectiles having a relatively high L/D ratio such as 10-25 either fired by a gun or rocket propelled wherein stability during the trajectory is obtained by the use of stabilizer fins.
The invention concerns the latter class wherein spin at slow rates is used to stabilize the projectile. To accomplish this fins are designed to produce a rotation about the longitudinal centerline at a rate somewhat above the natural aerodynamic pitching frequency of the particular projectile. This prevents erratic flight paths and permits good prediction of accuracies.
Use of high velocity APFSDS projectiles for defeat of armor is widespread due to the high performance capability of this type projectile. Production ammunition is now in use for gun sizes from 25 mm to at least 120 mm. However these projectiles, with their very high ratio of mass-to-frontal area and high muzzle velocities have the capability when fired of going long distances (measured in tens of miles) if they do not impact some target or terrain. This introduces considerable concern in tactical training since few test or training ranges are sufficiently large to contain such high energy projectiles over distances as extensive as may be required.
As a result an urgent need has developed for some effective means of providing a range limiting feature for such projectiles. Methods that have been used include explosive destruct and air drag increases caused by choked flow variations through orifices in conical afterbody configurations. However these methods suffer certain limitations and disadvantages from the standpoints of reliability, ballistic simulation, or ability to limit range. As a result a more effective means of limiting the range for training projectiles is still highly desired.